Handle BOM correctly

[ksgeograf]

This is an enhancement request to support BOM correctly in MapGuide.

Since Xml documents are also text documents, they are frequently prefixed with a Byte-order-marker, BOM.

MapGuide reads xml documents using the MgXmlUtil::ParseString, which does not look for BOM. This is by design, as ParseString is not intended to parse documents.

It is possible to upload an xml document with a BOM without any errors, but attempting to use the document will cause errors in MapGuide.

This is particularly annoying if the document is uploaded as a ResourceHeader, as that will make enumeration of the document fail.

The severity of this problem is low, because one can simply upload a correct document, and the error goes away.